In applications of switch-mode power supply and battery power supply circuit, circuit protection, for example, over-voltage protection (OVP), over-current protection (OCP) or over-temperature protection (OTP) is important. In prior art, a control chip is applied to monitor the voltage, current, temperature or other parameters of the protected circuit and thereby protects it. Since the control chip needs to consume quiescent current, it directly affects the operating efficiency of the protected circuit.
In prior art, the operating efficiency of circuit is generally improved through decreasing the quiescent current. However, the degree of decreasing quiescent current is limited. Therefore, the improvement of the operating efficiency is constrained.